The present invention relate to washing machines.
More specifically, the invention is aimed at a washing machine comprising a support structure in which is suspended a washing chamber in which a laundry drum is mounted to be rotatable, and in which detector means are provided, capable of providing electrical signals indicating the level of the washing liquid in said chamber, said detector means comprising an inductive transducer including a coil and an associated core, the relative position of which is variable according to the level of the washing liquid, such that the inductance of said coil varies accordingly.
Washing machines of that type have been produced and widely used for years. In such machines, the means for detecting the level of the liquid in the washing chamber typically comprise an inductive pressure transducer coupled to a so-called air trap by means of a small tube. The inductive pressure transducer comprises a rigid casing in which a diaphragm is disposed. When the level of the liquid in the washing chamber exceeds a predetermined level, a column of air is trapped between the air trap and the transducer and, as the liquid level rises, the pressure which the column of air exerts on the diaphragm increases. The diaphragm in turn brings about a corresponding relative displacement of the core with respect to the associated coil. The consequent variation in the inductance of the coil may be detected in various ways. The coil may for example be inserted in an oscillatory circuit, and the variation in its inductance brings about a corresponding variation in the resonant frequency of that circuit.
It is convenient to be able to have available in the washing machine information regarding the load or weight of the laundry introduced into the drum. For this purpose it is known to provide a washing machine with a suitable sensor, generally termed a weight sensor.
The addition of a weight sensor involves an increase in cost, and in complexity, of the washing machine and of the relevant control system.